1. Field of the Invention
This invention relates to a rotation detecting mechanism for a tape recorder. More particularly, it relates to a rotation detecting mechanism for a tape recorder provided with a so-called auto reverse mechanism for automatically reversing the running direction of a recording magnetic tape when the tape end is reached in the recording or reproducing mode or with a so-called auto shut-off mechanism for automatically setting the tape recorder to a stop mode when the tape end is reached, wherein the rotation or cessation of rotation of reel blocks rotating with the tape feed or of various gears or pulleys rotating by the operation of a driving electric motor is sensed for detecting the tape end to reverse the running direction or stop the running of the recording magnetic tape.
2. Related Art Statement
There has been proposed a tape recorder adapted for recording and/or reproducing information signals on a recording tape, such as a magnetic recording tape, wherein the tape recorder is provided with the so-called auto-reverse function of reversing the tape feed direction or the so-called auto shut-off function of establishing a stop mode when the tape arrives at its end in the recording and/or reproducing mode.
This type of tape recorder is provided with rotation sensing or detecting means whereby cessation of rotation of rotating members such as reel blocks, gears or pulleys rotated with the feed of the recording tape may be sensed.
As the rotation sensing or detecting means, there is known optical sensing means for sensing rotation of a rotating member wherein the rotating member is provided with portions of different light reflectivity or slits, the light is irradiated on these portions or slits and changes caused in the intensity of the light reflected from or transmitted through the rotating member are sensed for sensing the rotation or cessation of rotation of the rotating member. Also known are magnetic or electrical sensing means for sensing the rotation of the rotating member.
For sensing the rotation of the rotating member by optical means as the rotation detecting means for a tape recorder, it is necessary to use light emitting and light receiving elements as well as the electrical circuitry for driving sensing elements, thus complicating the construction of the tape recorder.